This invention relates generally to valves and valve systems, and specifically to position sensors for high-temperature valves and related flow control devices. In particular, the invention concerns a direct-feedback position sensor for valve components exposed to high operating temperatures, including bleed valves for rotary compressors, gas turbine engines and other turbomachinery.
Turbine engines provide efficient, reliable power for a wide range of industrial applications, including aviation, power generation, and commercial heating and cooling. Gas turbine engines (or combustion turbines) are built around a power core comprising compressor, combustor and turbine sections, arranged in flow series with an upstream inlet and downstream exhaust. The compressor compresses air from the inlet, which is mixed with fuel in the combustor and ignited to generate hot combustion gas. The turbine section extracts energy from the expanding combustion gas, and drives the compressor via a common shaft. Energy is delivered in the form of rotational energy in the shaft, reactive thrust from the exhaust, or both.
Large-scale gas turbine engines typically include a number of different compressor and turbine sections, which are arranged into coaxially nested spools. The spools operate at different pressures and temperatures, and rotate at different speeds. The individual compressor and turbine sections are further divided into a number of stages, which are formed of alternating rows of rotor blade and stator vane airfoils. The airfoils are shaped to turn, accelerate and compress the gas, and to generate lift for conversion to rotational energy in the turbine.
In ground-based industrial applications, the turbine shaft is coupled to an electrical generator or other external load. In aviation applications, the compressor is typically coupled to a propeller, propulsion fan or lift rotor, with or without a gearbox to control rotational speed. In jet engine applications, the compressor also provides bleed air for environmental functions including cabin pressurization and temperature control, and for accessory systems such as de-icing and other pneumatics such as airflow through heat exchangers.
Bleed air systems are subject to constantly changing operational demands, requiring precise pressure, temperature and flow control because overall engine efficiency depends on the engine compression ratio. Moreover, there is a continual motivation to raise operating temperatures and pressures, increasing thermal stress on bleed valves and other flow control components mounted to the compressor casing, or in other locations along the core gas path.